The present invention relates to novel hydrazone compounds and to their preparation and use, and more particularly to hydrazone compounds represented by the general formula ##STR3## wherein Ar represents a condensed ring, such as a naphthalene ring, an anthracene ring, or their substituted rings; a styryl group or its substituted groups; or a heterocyclic ring, such as a pyridine ring, a furan ring or a thiophene ring; and to a process for preparing the hydrazone compounds by allowing aldehydes represented by the formula Ar-CHO, wherein Ar represents the same as mentioned above, to react with 1-methyl phenylhydrazine represented by the formula ##STR4## in accordance with the following equation: ##STR5## The thus prepared hydrazone compounds are extremely useful charge transport materials for use in, for example, electrophotographic photoconductors of the type comprising an electroconductive support material and a photosensitive layer containing a charge generation material and a charge transport material.
As is well known, a variety of substances with --NH.sub.2 groups condense with carbonyl compounds to give &gt;C.dbd.N-- compounds and water. These reactions usually require catalysts. The condensation reactions may proceed through initial addition of an amine reagent to the carbonyl group with subsequent elimination of water from the two molecules, whereby an unsaturated nitrogen-containing derivative is formed: ##STR6## By the above-mentioned condensation reactions, many hydrazone compounds have been prepared and some of them have been found to be useful as electrophotographic materials as is disclosed in British Pat. No. 930,988, No. 933,363, No. 1,156,151 and No. 1,324,684 and U.S. Pat. No. 3,756,884.
However, no prior art reference of which we are aware suggests the hydrazone compounds according to the present invention and their preparation and use.